CAPE CANAVERAL, Fla. — NASA’s Maven spacecraft arrived at Mars late Sunday after a 442 million-mile journey that began nearly a year ago.

The robotic explorer fired its brakes and successfully slipped into orbit around the red planet, officials confirmed.

“I think my heart’s about ready to start again,” said Maven’s chief investigator, Bruce Jakosky of the University of Colorado. “All I can say at this point is, ‘We’re in orbit at Mars, guys!’”

Now the real work begins for the $671 million mission, the first dedicated to studying Mars’ upper atmosphere.

Flight controllers in Colorado will spend the next six weeks adjusting Maven’s altitude and checking its science instruments, and observing a comet streaking by. Then in early November, Maven will start probing the upper atmosphere of Mars. The spacecraft will conduct its observations from orbit; it’s not meant to land.

Scientists believe the Martian atmosphere holds clues as to how Earth’s neighbor went from being warm and wet billions of years ago to cold and dry. That early wet world may have harbored microbial life, a tantalizing question yet to be answered.

NASA launched Maven last November from Cape Canaveral, the 10th U.S. mission sent to orbit the red planet. Three earlier ones failed, and until the official word came of success late Sunday night, the entire team was on edge.

“I don’t have any fingernails any more, but we’ve made it,” said Colleen Hartman, deputy director for science at Goddard Space Flight Center in Greenbelt, Maryland. “It’s incredible.”

The spacecraft was clocking more than 10,000 mph when it hit the brakes for the so-called orbital insertion, a half-hour process. The world had to wait 12 minutes to learn the outcome, once it occurred, because of the lag in spacecraft signals given the 138 million miles between the two planets on Sunday.